Rotor grinder



Dec. 14, 1948. J. H. HOERN ET AL 2,456,060

' ROTOR GRINDER Filed Dec. 29, 1945 6 Sheets-Sheet 1 'i" U I I m &

. INVENTOR.

Joss u H. H0525) y I Cure-r15 GJ=A J=EE Magi M TQRNBLS Dec. 14, 1948. J. HvHOERN ETAL ROTOR GRINDER 6 Sheets-Sheet Filed Dec. 29, 1945 INVENTOR. JOSEPH H. HOEIZN y (Luz-n5 GLPAME.

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Dec. 14, 1948. H, HOER'N T AL 2,456,060

ROTOR GRINDER Filed Dec. 29, 1945 6 Sheets-Sheet 3 JOSEPH H.HOERN y CURTIS Gr. PNQDEE Dec. 14; 1948. J. H. HOERN ETAL 2,456,060

ROTOR GRINDER Filed Dec. 29, 1945 I 6 sheets-sheep:

INVENTOR.

H & i 1 JOSEPH HHozaN BY Cure-ms GPaamaz F i M /6%,

ATTORNEYS Dec..14, 1948. J HOERN ET AL 2,456,060

ROTOR GRINDER Filed Dec. 29, 1945 s She'ets-Sheet 5 INVENTOR. JOEPH H. HOEEN y Cums Gm Mi 74 RTTORNBK 5 Dec. 14, 1948. J. H. HOERN EI'AL ROTOR GRINDER a sheets-sheet 6 Filed Dec. 29, 1945 I h M v III "I Y INVENTOR. JO5EPH HHpazu y Cuzns GPARDEE WW9 Arr-012N516 Y Patented Dec. 14, 1948 ROTOR GRINDER Joseph H. Hoern, Birmingham, and Curtis G. Pardee, Detroit, Mich., assignors to Eaton Manufacturing Company, Cleveland, Ohio, a

corporation of Ohio Application December 29, 1945, Serial No. 638,184

Claims.

This invention relates to gears or rotors and more particularly to a machine for grinding or finishing and generating to a prescribed form gears or rotors of a peculiar character.

Broadly the invention comprehends a machine for finishing or grinding to desired precision and accuracy gears or rotors, such as the rotors of rotary pumps of the Gerotor type, said pumps consisting essentially of an outer ring or rotor having a plurality of identical teeth in its inner periphery equally, angularly spaced from one another, and equidistant from the central axis of the outer rotor, and an inner rotor having a plurality of teeth on its outer periphery one less in number than the outer rotor equally, angularly spaced from one another equidistant from the central axis of the inner rotor, and of a conjugate form to the teeth on the outer rotor. The inner rotor is adapted to be received within the outer rotor and mounted centrally thereto whereby upon rotation of the outer rotor and inner rotor about their respective axis the teeth of the inner rotor maintain substantial contact with the teeth of the outer rotor over a major if not the entire rotational position thereof so as to provide a plurality of pumping chambers between the cooperating inner and outer rotors, which chambers increase in volume in the direction of rotation from a position of full mesh between the teeth of the outer and inner rotors to the position of open mesh thereof and decrease in volume from the latter position to the former position in the direction of rotation of the rotors. It is essential in the construction of pumps of this type that a high degree of precision and accuracy be maintained between coa-cting teeth of the inner and outer rotors; and accordingly, it is the premise of the instant machine to roduce said result.

Although various machines have been constructed or devised to accurately cut or grind gears or rotors of the aforementioned type, none has attained as high a degree of accuracy in the production of said rotors as is desired for the purpose of producing a highly eiiicient pump. The instant development was undertaken to remedy this condition and as such provides an effective structure minimizing to the utmost factors tending toward inaccuracy in the production of gears or rotors of this type.

An object of this invention is the provision of a machine for finishing rotors to a high degree of precision and accuracy.

Another object of the invention is the provision of a machine having means incorporated therein for diminishing the amount of inaccuracy in 2 the finished machining of rotors for Gerotor type pumps.

A further object of the invention is the provision of a machine for finish machining gear or rotors of a peculiar character wherein the gear supporting arbor is rotated about its axis while the axis thereof is simultaneously rotated in an eccentric arcuate path, said machine having means incorporated therein adapted to counterbalance the eccentric motion and unbalance of the machine.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings, forming a part of the specification; and in which:

Fig. 1 is a side plan View of the rotor finishin machine as related to its cooperating grinding or finishing tool;

Fig. 2 is a vertical cross sectional end view of the machines gear box taken along line 2-2 Fi 1;

Fig. 3 is a vertical cross sectional view taken along line 3--3 Fig. 2;

Fig. 4 is an end plan view looking in the direction of line 4-4 Fig. 1;

Fig. 5 is a vertical cross sectional end view of :the gear driving means for the machine taken along line 5-5 Fig. 1;

Fig. 6 is a fragmentary vertical cross sectional view taken along line B-6 Fig. 2;

Fig. '1 is a vertical cross sectional view taken along line 1--1 Fig. 4;

Fig. 8 is a cross sectional view taken along line 88 Fig. 1;

Fig 9 is a cross sectional view taken along line 9-9 Fig. 4;

Fig. 10 is a fragmentary vertical cross sectional view taken along line |0-| 0 Fig. 1;

Fig. 11 is a vertical cross sectional view taken alongline H-l I Fig. 1; and

Fig. 12 is a cross sectional view of the idler gear taken along line l2| 2 Fig. 2.

It has become vitally important in the production of gears or rotors, especially rotors for use in rotary pumps, to provide rotors of high precision and accuracy so as to obtain a gear rotor type of pump of high or ultimately maximum eificiency. The presently developed machine, because of structural modifications and improvements over previously devised machines of this nature, i capable of commercially finish cutting or grinding pump rotors in large quantities and as exact duplicates of one another within finite limits. This machine is designed to finish machine to desired precision and accuracy inner rotors for Gerotor type rotor pumps which have been previously stamped, out, or roughed out to approximate size and form by any suitable means.

The general structure of the present machine includes (1) a base with precision bearings and two main drive shafts arranged in parallel relationship and having a mutual driving gear therefor so as to provide for common direction of rotation of the shafts, the driving motion therefor being derived. from an external source; (2) a main oscillating body with precision eccentric sleeves fitted into precision bearings and fitted over and keyed. to the main drive shafts within the base; (3) a precision spindle geared direct to one of the eccentric sleeves within the base in a ratio to suit the number of teeth in the rotor to be ground; (4.) a counterweight to counterbalance the motion. of the machine gearedv through an idler ear to provide proper direction of rotation; (5) an arbor centered with the spindle and fixed thereto supporting a group of rotors to be ground; and (6) a tailstock mounted on the oscillating body having-means therein for supporting one end of the arbor disposed axially from the spindle.

The arbor is adapted to have a multiple of rough cut rotors mounted and clamped there on such that the semi-finished rotors may be loaded on one arbor at a point remote from the machine while another arbor supporting a second set of rotors is in machining position in the machine.

The group of rotors mounted on the arbor with the arbor in operative position in the machine during the rotation and oscillation thereof produce a desired locus of contact with the associated grinding wheel or any other appropriate finishing tool mounted on an axis transverse to the arbor spindle and rotatable in a plane parallel to the arbor axis so as to produce a finished developed profile on each rotor. The grinding wheel is rotatable solely and positively about its axis, the axis of said rinding tool being movable axially parallel to the axis of the arbor so wise suitably secured to a machine bench or framework, as shown by Fig. i. The base it! has journaled upon suitable bearings l2 and M in one end thereof a driven shaft 56 mounted centrally of the base having keyed at one end externally of the base a pulley i8 adapted to be connected to and driven by a power source, not shown, and a spur gear 2t splined to the other end adjacent bearings i 3.

Gear 20 as shown by Fig. 5 meshes respectively with and drives identical gears 22 and 24 in the same: direction of rotation and rate of speed, said split gears 22 and 24 being splined respectively upon rotatable shafts 26 and 28 journaled in the base Ill, shaft 26 shown by Fig. 7 illustrating the manner in which the shafts are journaled in the base. Shafts 2G and '28 are disposed apart an equal distance from the center of base In and as such uniformly support an oscillating body 39 journaled thereon. As shown by Fig. 7, shaft 26 is rotatably mounted upon bearings 32 supported in bearing post 35 of base HI and at its other end on bearings 36 supported on bearing post 38 of base it. The shaft 26 has mounted on the ends thereof a pair of equal eccentric sleeves 40 and 42 supporting through 4 bearings 44 and 46 mounted thereon the oscillating body 30, said eccentric sleeves providing for revolving the body in an orbit of radius equal to the eccentricity predeterminedly desired between the inner and outer rotors of the pump. The shaft 28 although not shown in its entirety as shaft 26 likewise is journaled in base IQ and correspondingly has eccentric sleeves and bearings supporting the body 30.

The body 30 comprises a main body portion 43. a gear box 5! a base portion 52, and a bed 5-l.

Shaft 26 has secured on one end thereof a split gear 56 adapted to mesh with and drive a much largersplit spur gear 58, said gear 58 being in turn splined upon a spindle shaft 60 journaled in bearings 62 and 64 mounted in a sleeve 66 pressed. into the main body portion 50 of body 48. The gear ratio between gears 56 and 5G is predetermined depending on the number of teeth on the rotors that are to be ground.

Shaft 23 has secured on one end. thereof a split spur gear 6.8 adapted to mesh with and drive an idler gear 70 rotatably mounted upon body portion 5 0 of body 48, said gear l0 meshing with a gear 12to thus transmit rotation from gear 68 to gear 72. Gear 10. merely actsto provide for rotation of gear 12 in the same direction of rotation as shafts 26 and 28 and oscillating body 38 whereby a counterweighed shaft 74 journaled on bearings 16 and E8 in the base of body 50, upon which the gear 12 is splined operates to counterbalance the motion of the machine and thus reduce oscillating unbalance induced in the machine as the oscillating body is eccentrically actuated with respect to the base of the machine.

The base 52 of the-body 30 has mounted there on at one end axially removed from the spindle 60 a tailstock axially slidable on the base toward and away from the spindle as requirements necessitate. A; dead center 82 axially slidable in the tailstock is normally resiliently held in the direction of the spindle by a spring 84 and is released from said extended position by a crank lever mechanism v8t mounted on the tailstock.

An. arbor 38- adapted to mount the rotors to be machined is secured between the dead center 82 of the tailstock and a head 80 constituting part of the spindle, said arbor being fixedly secured in head'QU by a locking dog 92 so as to be rotatable therewith upon rotation'being imparted to spindle 60 through. its gear train.

A bolt 94 mounted on wedge pins 96 fitted in main body portion 54 of body '30 serves to securely lock sleeve 66 in the body.

Several suitable lubrication cups, reservoirs, and inlets, such as 98' are located at strategic points in the machine to provide effective lubrication to highly essential moving parts of the machine for the purpose of forestalling any possible binding of the parts thereof tending to cause inaccuracy of operation of the machine.

A steady rest I00 provides a supporting means for the arbor at a point between the tailstock and spindle head so as to suitably support the arbor and rotors mounted thereon.

A grinding wheel I02 or other suitable finishing tool fragmentarily shown is adapted to be mounted upon an axis transverse to the axis of the arbor and rotors 04, rotatable in a plane parallel to the axis of the arbor and shiftable during machining operation in the plane of its rotation.

In a normal operation of the machine with the arbor mounted in rotative position having a group of rough cut semifinished toothed rotors located thereon upon driving pulley i3 from a power source, not shown, the arbor is rotated at a speed corresponding to the gear train speed connecting the pulley with the spindle til.

With rotation of the gear 28 the gears 22! and 24 are driven therefrom in the same direction causing rotation in unison therewith shafts 26 and 28 respectively and eccentric sleeves 40 and secured at the opposite ends of shafts 26 and 28 thus effecting an oscillation of body 3!! corresponding to the amount of eccentricity provided between the eccentric sleeves and the axis of their supporting shafts.

The gear 565 fixedly secured to shaft 26 together with rotation of shaft 23 imparts its rotation to gear 58 thereby providing for rotation of spindle shaft fill and the arbor and rotors driven by the shaft 50, said spindle, arbor, and rotors being rotated at a speed as governed by the comparative gear ratio between gears 56 and 58, said ratio depending on the number of teeth on the rotors to be finished.

The speed of rotation of the arbor and the eccentricity or oscillation of the body is such as to provide the desired arcs of contact between the grinding tool H92 and rotors IM to thus provide a finished developed profile on the rotors of high precision and accuracy.

Simultaneously with the rotation of the spindle iii) and oscillation of the body 48 the rotation of shaft 23 is transmitted to counterweight shaft M by way of gear 98, idler 7E, and gear l2 splined on shaft 74. In addition to the eccentric weight distribution of shaft M a weight I06 is secured to the shaft in accordance with the amount of counterweight required as different sizes of rotors are ground, said weight being replaceable to counterbalance the unbalance affected by the weight of the body load as it is oscillated, wherein the axis of the spindle and arbor generate a circle eccentric to the axis of shafts 26 and 2B.

As the body 43 is oscillated and the spindle rotated, a point on the periphery of the rotors generates a curve in conformity to the profile of the rotors desired whereby the grinding wheel I02 contacts and grinds the outer periphery of the rotors to finish size and concentric accuracy, said wheel H32 being slowly moved across the rotors in a plane lying parallel to and passing vertically through the central axis of the machine. 7

The gears 22, 2d, 56, 58, 68, and 12 are all of split construction and adjustable to compensate for wear in tooth form so as to provide for con tinued efficient and accurate operation of the machine.

Upon finish machining or grinding of a group of rotors the dead center of the tailstock is retracted and the arbor released on the other end from the dog on the spindle so that the rotors are free to be removed from the machine preparatory to placing another arbor mounting a different group of rotors to be ground upon the spindle and dead center of the tailstock. In this manner it is possible to provide for assembling and cutting of rotors upon an arbor While at the same time machining and cutting of rotors that are in operative position in the machine thereby affecting a time saving factor.

This completes the grinding phase of operation of the machine through its stages of rotation and oscillation with the rotors in operative position with relation to the grinding Wheel.

While this invention has been described in connection with certain specific embodiments, the

principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention, therefore, is limited only as indicated by the scope of the appended claims What we claim is:

1. In a machine for generating an inner rotor conjugate to an outer rotor having a plurality of internal peripheral teeth, a base, a pair of similar rotatable shafts journaled in the base, similar eccentric sleeves on the shafts, a body journaled on the sleeves for eccentric motion thereabout, a spindle journaled for rotation in the body, means for rotating the shafts in unison, means for coupling the spindle to one of the shafts, means driven from one of the shafts for counterbalancing eccentric motion of the body, said spindle being symmetrically arranged relative to the shafts and counterbalancing means and a finishing tool rotatable about an axis transverse to the spindle and in a plane parallel to the axis of the spindle.

2. A machine for generating external peripheral teeth on a pump inner rotor comprising a pair of rotatable shafts arranged in parallel, common means for driving the shafts in the same direction and at the same rate of speed, a body eccentrically journaled on the shafts, a spindle journaled in the body, gear means coupling one of the shafts to the spindle and a counterweight journaled in the body extending parallel with the shafts and arranged substantially intermediate thereof and geared to the other shaft for counterbalancing the eccentric motion of the body.

3. In a machine for grinding an inner rotor for a rotary pump of the internal gear type, a pair of substantially identical rotatable shafts, a power source for the direct driving of the shafts, a body eccentrically journaled on the shafts providing for oscillatory motion of the body upon rotation of the shafts, a spindle journaled in the body extending parallel to and vertically disposed relative to the shafts, means for rotating the spindle in geared relationship to the shafts, a means driven from one of the shafts in unison therewith for counterbalancing the oscillatory motion of the body and spindle.

4. A machine for generating external peripheral teeth on inner rotors of internal gear pumps comprising a spindle adapted to carry the rotors to be machined, means for rotating the spindle about its axis, means for moving the spindle in an eccentric path, means for counterbalancing the movement of the spindle, and rotatable means adapted to engage the rotors carried by the spindle effective to provide for the generation of the teeth on the rotors, said spindle, the means for eccentrically rotating the spindle and the means for counterbalancing the spindle movement all being arranged parallelly and symmetrically to one another.

5. A machine for generating external peripheral teeth on inner rotors of internal gear pumps comprising a stationary base member, a pair of similar shafts rotatably journaled in the base, means common to both shafts arranged centrally therebetween providing for the rotation thereof in the same direction and at the same rate of speed, a body eccentrically journaled on the shafts for eccentric motion thereabout, a spindle journaled for rotation in the body extendin parallel to the shafts and being vertically centrally disposed thereof adapted to be moved eccentrically with the body, means for coupling one of the 7 shafts to the spindle to provide. for the rotation thereof, and means driven from the other shaft for counterbalanoing the eccentric motion of the body and spindle.

JOSEPH H. HOERN. CURTIS G. PARDE'E.

REFERENCES CITED Number 8. UNITED STATES PATENTS Name Date Landis May 28, 1907 Marburg Mar. 23, 1926 Braren Aug. 4, 1931 Nichols Apr. 9, 1935 Mossdorf Jan. 24, 1939 Horton May 30, 1944 

